Fingerprint Sensor Array Electrode Design for Touch Performance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive fingerprint sensors face issues with increased mutual capacitance in touch screen systems, leading to deteriorated touch performance and dead zones around the fingerprint sensor area, due to the integration of high-resolution sensor arrays and ICs on silicon wafers, which complicates configuration and increases thickness.
Innovation Solution
A fingerprint sensor array is designed with a fine pattern of transparent and low-resistance metal electrodes, arranged in a specific configuration with insulating layers to reduce electrical resistance and mutual capacitance, preventing dead zones and maintaining touch performance by using transparent conductive materials like ITO and low-resistance metals like Al or Ag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution sensor array and IC are integrated using silicon wafer, then fingerprint sensing precision is improved, but device complexity and non-display area size are increased
Solution Approach 1:
The patent merges the fingerprint sensor array with the touch sensor screen by integrating both sensing functions into a single electrode structure. The same electrode array serves dual purposes: fingerprint capacitance sensing and touch detection, eliminating the need for separate sensor assemblies and reducing device complexity while maintaining high-resolution fingerprint sensing capability
2Adaptability or versatility
If separate fingerprint sensor is disposed in screen area, then fingerprint sensing function is added, but touch performance deteriorates due to increased mutual capacitance
Solution Approach 1:
The electrode array is designed to perform multiple functions simultaneously: it acts as both the fingerprint sensing electrodes and the touch sensing electrodes. By using the same electrode structure for both fingerprint and touch detection, the patent avoids the mutual capacitance interference problem that occurs when separate sensor arrays are stacked, thereby maintaining reliable touch performance while adding fingerprint sensing capability
3Area of stationary object
If push button and fingerprint sensor overlap, then space is saved, but thickness is increased and sensing area is limited by push button size
Solution Approach 1:
The patent eliminates the need for a separate push button by integrating the fingerprint sensor directly into the touch screen electrode structure. The fingerprint sensing function is embedded within the flat electrode array, removing the mechanical protrusion and reducing overall device thickness while maximizing the usable sensing area without being constrained by push button dimensions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves fingerprint sensing precision and maintains the resolution of both the fingerprint sensor and display device by reducing electrical resistance and mutual capacitance, ensuring effective touch performance without dead zones.
Implementation Method 1
a difference in the amount of electricity charged between ridges which touch the fingerprint sensor and valleys is used
Implementation Method 2
each of the plurality of first electrodes including at least one of: a first transparent electrode including a transparent conductive material and a first metal electrode including a low-resistance metal material
Data Source
AI summary
Provided are a fingerprint sensor and a display device including the same. A fingerprint sensor array includes: a plurality of first electrodes arranged in a first direction, each of the plurality of first electrodes including at least one of: a first transparent electrode including a transparent conductive material and a first metal electrode including a low-resistance metal material; a plurality of second electrodes arranged in a second direction crossing the first direction, each of the plurality of second electrodes including at least one of: a second transparent electrode including the transparent conductive material and a second metal electrode including the low-resistance metal material; and an insulating layer between the plurality of first electrodes and the plurality of second electrodes to insulate the first electrodes from the second electrodes.